Spectroscopic characterization of rhino viral protease 2a: Zn is essential for the structural integrity
✍ Scribed by Tilman Voss; Rainer Meyer; Wolfgang Sommergruber
- Book ID
- 105356354
- Publisher
- Cold Spring Harbor Laboratory Press
- Year
- 1995
- Tongue
- English
- Weight
- 545 KB
- Volume
- 4
- Category
- Article
- ISSN
- 0961-8368
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✦ Synopsis
Abstract
Recently, protease 2A of human rhinovirus 2 (HRV2 2A) was shown to require a zinc ion for the formation of an active enzyme although zinc is not involved mechanistically. The data presented clearly show that the zinc ion bound to a picornaviral‐specific motif represents an essential component of the native structure, probably representing a new Zn‐binding motif. This structure, containing mostly β‐strand elements as shown by CD spectroscopy, changes drastically upon removal of zinc. The zinc‐depleted form does represent an intermediate with mostly unchanged secondary structure, but not a fully denatured random coil as obtained by guanidinium hydrochloride. This is indicated by the blue‐shifted fluorescence spectra and by CD. The native protein exhibited a cooperative phase transition at 53 °C. In contrast, the zinc‐depleted form did not show any transition at all, again demonstrating the stabilizing role of the zinc ion. A structural intermediate was observed during thermal and pH denaturation that may represent a molten globule, as suggested by its ANS binding.